The present invention relates to an apparatus for supplying a liquid under a constant pressure, for example, for use in supplying a liquid to containers each in a specified amount while the containers are being transported by a conveyor.
Such apparatus are already known which comprise a supply tank having a supply outlet, a pressurizing unit for supplying pressure air to the supply tank, and a control unit for controlling the pressure of the air in accordance with alterations of the level of a liquid in the supply tank so as to give a constant pressure to the liquid flowing out from the supply outlet.
The conventional apparatus requires pressure air and is therefore complex and expensive. The apparatus is further cumbersome to handle because there is a need to input initial data, such as the liquid level, to the control unit.
The main object of the present invention is to provide an apparatus for supplying a liquid under a constant pressure which requires no pressure air and which is inexpensive and easy to handle.
The apparatus of the invention for supplying a liquid under a constant pressure comprises a supply tank disposed at a higher level than articles to be supplied with the liquid, an overflow plate partitioning the interior of the supply tank into a main tank compartment and an auxiliary tank compartment, a supply pipe having an upper end connected to the main tank compartment and a lower end positioned to oppose the article, replenishing means for supplying a replenishment of the liquid to the main tank compartment at a rate in excess of the rate of supply by the supply pipe per unit time, means for transferring the liquid from the auxiliary tank compartment to the main tank compart at a rate in excess of the rate of supply, and control means for operating the replenishing means and stopping the transferring means upon the liquid level in the auxiliary tank compartment reaching a predetermined low level and for stopping the replenishing means and operating the transferring means upon the liquid level reaching a predetermined high level.
With the apparatus of the present invention, the replenishing means and the transferring means are brought into and out of operation as controlled in accordance with the liquid level in the auxiliary tank compartment. The liquid is supplied to the main tank compartment at a rate in excess of the rate of supply by the supply pipe per unit time, by the replenishing means while this means is in operation or by the transferring means while the replenishing means is out of operation. Accordingly, the main tank compartment is always in an overflow state, permitting the liquid to maintain a constant level therein and giving a constant pressure to the liquid to be supplied to articles (containers) through the supply pipe. Accordingly, the liquid supplying apparatus provided requires no pressure air and is inexpensive and easy to handle.